Drill



April 1, 1930. T GRANT 1,752,524

DRILL Filed June 28, 1928 INVENTOR ATTORNEY.

Patented Apr. 1, 1930 THOMAS GRANT, OF GILLESPIE, ILLINOIS DRILL Application filed .Tune 28, 1928. Serial No. 288,861.

This invention relates to certain new useful improvements in drills for coal, rock and other material, the peculiarities of which will be hereinafter fully described and claimed.

.5 The main object of my invention is to provide a drill adapted to maintain its operative length and effective usefulness, and hence never needing to be discarded; secondly, one that can be readily maintained in its sharp operative condition Without the delay of sending it to the tool dresser for regrinding; and thirdly, to features of construction hereinafter described and claimed.

In mining coal for instance, my drill eliminates the labor of taking a heavy drill to the surface for regrinding; it also maintains its operative length, instead of being continually shortened by wear and regrinding till the body has to be thrown away as useless. With a drill of my construction readily maintained in its effective condition, a miner using it does not lose time and production by continuing to use a dull drill, as is often the case.

In the accompanying drawing in which like reference numerals indicate corresponding parts,

Fig. 1 represents a drill embodying my invention and partly in section and Fig. 2, another view of the operative end of the same.

Referring to the drawing, the numeral 1 designates the body of the usual screw form or other suitable shape, that is fastened by a shank 2 in a suitable operative mechanism furnishing power to rotate it as usual.

A suitable head 3integral or otherwise, on the said body, is provided with multiple sockets for the reception of multiple cutting tools,a central socket 4 in the axis for a pilot drill 5, and two (or more) auxiliary sockets 6 that are preferably inclined to the axis and more or less intersecting said central socket. In these auxiliary sockets which are squa-reor otherwise-in cross section, are mounted corresponding shanks 7 of multiple cutters having tips 8 projecting forward and outward laterally beyond the normal diameter of the body and preferably inclined to the central axis of the head and body as W shown in Fig. 1. I

The upper sides of said cutters lie in the of all the cutters against theshoulders formed by the inner ends of the auxiliary sockets, or

otherwise fastens them.

The pilot drill extends in front-axially of the cutters as shown, so as to drill a comparatively small hole ahead in the extended axis of the body, while the follow up and bore out the between the circumference auxiliary cutters annular portion of the pilot drill and the larger circumference of the operative circle of the outside of the auxiliary cutters which do the major part of the work.

The shanks 7 of said auxil iary cutters when slidably inserted in their sockets, extend slantingly into said central socket, and are engaged and held by the shank 9 of the pilot drill (or other means) which is preferably screwed into its socket 4.

For further security of these cutters, a notch 10 near the end of each shank of the cutters, end of the shank of the pil is engaged by the ot drill, or other means, inserted in said axial socket. These multiple cutting tools may be otherwise fastened in the head, and their tips may be of other shape than sh own without departing from the spirit of my invention.

It is evident that these detachable cutting tools when worn may be readily replaced by sharp ones; that the lengt h of the drill is maintained substantially the same; that the body and shank of the era 1 will last indefinitely; and that the operativelength will be easily maintained in effective condition at little less of time and money for replacement of the comparatively small cutting tools of my construction.

To the best of my knowledge, such a drill as above described hasnot my invention thereof, and I broadly.

I claim:

been used before therefore claim it ably mounted in said ineli ned sockets with signature;

portions of their inner ends extending through said apertured Wall into said axial socket, and a screw mounted in said axial socket and having the circumferential corner edge of its inner end engaged with the side face of the portion of each cutter extending into said axial socket, substantially as described,

2. A drill of the class described, comprising a head having a threaded axial socket and individual multiple sockets inclined to the C(5I1- tral axis and intersected for part of their diameter by said axial sockets forming apertures in its Wall, multiple cutters slidably mounted in said inclined sockets with portionsof their inner ends and side faces extending through said apertured Wall of the axial socket and having notches on their inner side faces, and a pilot drill having a threaded shank fitting into said axial socket and having the circumferential corner edge of its inner endengaged with the notches'of said cutters, substantially as described.

In testimony whereof I have affixed my THOMAS GRANT. 

